Hemp Update #13

Spider Mites & Leafminer on Hemp:

The last 2 weeks have shown a definite increase in the spider mite damage to the crop.  Pictures on the left are of typical damage.  Two-spotted Spider Mites are what have been identified.   The damage rages from light speckling to marked discoloration/bronzing.  The hot/dry of last week spurred on populations and increased levels of damage.  When the plant is stressed from lack of water and high temperatures the damage is more noticeable.  To see the spider mites, you would likely need a lens.  They are quite small but are identified by the 2 prominent spots on their back.  Sometimes, when populations have decreased, you can still see webbing or frass (tiny black specks of excrement) on the undersides of leaves.  The rain on Sunday/Monday decreased populations in many fields.  The jostling and wetting dislodges them.

Spider Mite damage results in loss of photosynthetic area and could possibly lead to reduced production.  Possibly, because the mites create wounds with their feeding, there would be increased disease infections from these wounds.  Spider mites can come from weeds or neighboring crops such as corn or soybeans where they are a somewhat common pest.

Good factsheet on mites:  http://www.greenhouse.cornell.edu/pests/pdfs/insects/TSSM.pdf  This was written for greenhouse producers so it includes a section on the cyclamen mite which is not our concern in hemp in fields.

Photos: M. Ullrich & J. Gertin

Leafminer (right):

Several species of leafminers attack a wide range of crops.  You may see this mining in your crop from time to time as cycles of egg laying and larval feeding occurs.  The female lays an egg in between the layers of the leaf and the larvae feed on the leaf protected by the upper and lower coating of the leaf (making it pretty much impervious to pesticide applications).  The larvae matures, pupates and becomes and adult to repeat the cycle.  That’s why damage seems to quickly appear and then there is no new damage.  It is all on the cycle of the insects and they develop on growing degree days keeping the majority of the population all in the same cycle.

Thus far on hemp, damage has been minimal.  Leafminers have preferred plants they seek out but many of the species will lay eggs on whatever they find.  Seeing a “patch” of damage is common.  Photo: J Gertin

Hemp Field Meeting (see attached flier)

August 15, 2019

Hudson Valley –  2 locations

1:00-3:00 PM

Hudson Valley Research Lab

 3357 Rt. 9W, Highland, NY 12528


6:00-8:00 PM

Fields of Brian Pawelski and Bruce Ludovicy

736 Pulaski Highway, Goshen, NY 10924

Register for either here: http://weblink.donorperfect.com/hempfieldmeeting

Daylength and Flowering:

Lengthening nights are what trigger flowering in hemp, and a few plants (non-autoflower) are beginning to show the starts of flower development.  Review past updates for how to identify males or hermaphrodites.  http://cceorangecounty.org/resources/hemp-updates

Price/Forecasting Monitoring:

A company has emerged that provides market data on hemp:


NYS Reiterates Position on CBD in Foods:

NYS reconfirmed its position in a letter to food processors this past week (attached) referring to their website language  https://www.agriculture.ny.gov/FS/general/food_businesses_resources.html#industry:

CBD in Food

This notice serves to clarify the New York State’s Department of Agriculture and Markets’ (Department) position on the inclusion of cannabidiol (CBD) in food products. The Department’s policy is: 

No food or beverage product may be made or sold in New York State if it contains CBD as a food, a food additive or an ingredient.

Food or beverage products that are found by Department inspectors, in either a processing facility or in the marketplace, to contain CBD are considered adulterated (FD&C Act, sec. 301(b) and AML, sec. 200). These products are subject to enforcement actions taken by the Department or the U.S. Food and Drug Administration (FDA). Enforcement actions may include:

  • Voluntary removal of products
  • Seizure and/or destruction of products
  • Issuance of a fine and/or a failing sanitary inspection

Please do not hesitate to reach out to our Division of Food Safety and Inspection at FSIWebInquiries@agriculture.ny.gov or our Division of Milk Control at MCDS@agriculture.ny.gov or (518) 457-1772 with any questions. For a list of frequently asked questions regarding CBD in food please click here. For a copy of the letter that will be distributed to licensee or permit holders click here.

Cornell Cooperative Extension does not endorse or recommend any product, service, individual, business or other entity.